Control of Physical Properties by the Matching between Rock Components and Pore Structure in Shale Oil Reservoirs

Shale oil reservoirs are extremely tight, making it fundamental to evaluate their physical properties to exploration and development efforts. These properties are closely linked to the rock components (RC) and pore structure (PS). The significant complexity and heterogeneity inherent in the RC and PS pose considerable challenges for assessing the physical properties of these reservoirs. In specific depositional environments, a matching relationship between RC and PS exists. Identifying this relationship and associating microscale PS attributes with macroscale physical properties can expose substantial variations within shale oil reservoirs, aiding in the selection of optimal layers for exploitation and improving development efficiency.

This study focuses on the shale oil reservoirs of the Lucaogou Formation (P₂l) in the Jimusar Sag, marked by mixed-source sedimentation. Using a combination of thin section observations, XRD, TOC analysis, and EDS analyses, it characterizes the RC within the designated area. Moreover, the investigation employs LTNA experiments, MICP tests, and SEM to detail the PS attributes. Based on these experiments, the research analyzes the matching relationship between RC and PS in the shale oil reservoirs and the connection between microscale PS and macroscale physical properties, highlighting the control of physical properties by RC and PS. The findings reveal that pore types in these shale oil reservoirs predominantly consist of small pores and mesopores. Small pores, developed within K-feldspar, quartz, and clay minerals, are chiefly dissolution pores; mesopores occur between dolomite or plagioclase grains, characterized by a regular pore morphology. Porosity is governed by the presence of micropores, mesopores, and macropores, while permeability is principally influenced by mesopores and macropores. This established relationship between RC and PS in this study offers a reference for the efficient development of the P₂l shale oil reservoirs and can serve as a foundation for research into fluid-solid interaction and flow characteristics in porous media.